Telegraph repeater system



Sept. 24, 1946. F, H, FAY ET AL 2,408,304

TELEGRAPH REPEATER SYSTEM File d Oct. 22, 1945 N Q N I I v i Q. g 1H d Q I u lto k? INVENTORS ZEZZZlg flEWeeUe BY a ATTORNEY Patented Sept. 24, 1946 OFFICE TELEGRAPH REPEATER SYSTEM Frank Homer Fay, Huguenot Park, N. Y., and Elmer William Reeve, Blainfield, N. J assignors to American Telephone and Telegraph Company, a corporation of New York Application ctober 22, 1943, Serial No. 507,230

- 1 1 This invention relates to telegraph systems. More particularly, this invention relates to repeaters for telegraph systems which are arranged 5 Claims. (01.178-73) to repeat signals simultaneously from any one of a plurality of stations to all of the other stations of the system.

Heretofore two telegraph. stations were connected to each other by two repeaters having balanced or difierential loops, one of suchloopsbeing associated with each telegraph station, each repeater serving to repeat the signals in opposite directions between the station with which it is graph station TS and through a circuit of re- I I associated and the repeater associated withthe other telegraph set; When adding a third telegraph station having a balancedor differential loop, the balanced loop systembeinga'rranged to permitsignaling from any one of the telegraph stations to theother stations simulta neously, it has been necessary heretoforefnot alone to provide a third :re'peater similar tothe other two,but also to furnish a single line'fre peater as a fourth repeater. Unless the fourth or single line repeater was added tothe other three repeaters of the system, it was impossible to transmit signals from any one, of the stations to all of the other stations simultaneously.

In accordance "with this. invention itris proposed to interconnect three or more stations to each other by but three repeaters and arrange the system so that any one ofthe stations may transmit signals to all of the other stations simultaneously. More generally, it is proposed to interconnect three or more difi'erenttelegraph stations to each other by repeaters which are equal in number to the number of telegraph stations in the system. The arrangement proposed single line repeater such as hasbeenfoundnecessary heretofore in such installations. The oInission of the single line repeater considerably re'-' sible to obtain such additional equipment,

This invention will be better understood from the more detailed description hereinafter following when read in connection with the accom- ,panying drawing showing one'embodiment of the L1, L2 and L3, respectively. Station A includes a key K1 and a sounder SD1, the station B a key K2 and a sounder SD2, and station C a key K3 and a sounder SDs. with the line terminal of a repeater RP1 at station D. The line L2 connects station B with the line terminal of a repeater RP2 at station D. The line L3 connects station'C, with the line terminal of-a repeater RPa at station D. The loop terminalsof repeaters RP1 and RPz are connected to each other through the equipment of a telepeater RP3 which maybe considered as the loop of repeater R1 3; The telegraph. station TS in,- cludes a key Kioand a, sounder SD10. This telegraph station may be located at the repeater stationD or it maybe some distance away from the repeater station D. The circuits of repeaters RP1 and RP; are of the. balanced or differential loop type and are the same as those heretofore embodied in repeaters interconnecting two telegraph stajtionssuch as A and B. The third repeaterRPa at station D, however, hasbeen modified so that it may be joined to the loop terminalsof the other tworepeaters at station D t0 enable, signals to be transmitted from vany one of the three (or more) stations to the other stations of the system simultaneously.

When no signals are being transmitted through the system, the keys at the various stations will be in their closed positions. The .current traversing the upper winding of the receiving relay RRi of repeater RPi will be in a marking. direcin accordance with this invention will omit the invention merely for the purpose of illustration. 4

Referring to the drawing, three telegraph stations located at widely diiferent points and designated .A, B and C are shown connectedto a common repeater station D 'by means of lines .tion and this current will exceed the current in a spacing direction traversing its lower winding, thereby holding the armature of relay 'RRi on its marking contact M. There will also be a large flow of current through. the. upper windingsof the sending and break relays SR1 and BK1 of repeater RP1, and through the lower windings of the break and sending relays BKg and' SR2. This current will be in a marking direction and suflicient in magnitude toovercome the spacing current flowing'in'the otherwindings of these relays. 'Thus the armatures of relays SR1,

BK1, 3K2 andSRzwillbe held on their marking contacts M. The marking currents just referred to will flow over a circuit which includes battery [Bathe armature and marking contact M of relay RRrthe upper windings o'f relays SR1 and BKI, resistor Z1, the upper winding of relay SR3 'of repeater RPs', the armature and marking c o n tact M of relay BK3 of repeater RP3, key K10 and thewinding of sounder SD10 of telegraph station TS, resistor Z2, the lower windings of relays The line L1 connects station A BK2 and SR2, the armature and marking contact M of relay RRz, battery Be and ground. There will also be a flow of current in the upper winding of the receiving relay RRz in a marking direction and of a magnitude which will exceed the current in the lower winding of this relay which is in a spacing direction, thereby holding the armature of this relay also on its marking contact M.

The upper winding of relay RR3 of repeater RPs will also receive current in a marking direction of greater magnitude than the current in the spacing direction flowing through its lower Winding, thereby holding the armature of relay RR3 on its marking contact M. The lower wind ing of relay SR3 may be considered as receiving opposing currents from batteries B1 and Ba. The battery B1 is connected to the lower winding of relay SR3 over a circuit which includes battery B7, resistor Z3, the coil CI-I, the armature and marking contact M of relay RR3, and the lower winding of relay SR3 and ground. The current from battery B7 will be a large current of, for example, 60 ma. and it will be in a spacing direction in the lower winding. The current from battery Bs will flow over a circuit which includes battery B8, resistor Z4, resistor Z5, the lower winding of relay SR3 and ground. This current will be of a smaller magnitude of, for example, 30 ma, and it will flow in the opposite direction tending to move the armature to its marking contact M. However, the current from battery B7 will overcome that of battery B3, yielding a resultant current of about 30 ma. which is in a spacin direction. At the same time current will be traversing the upper winding of relay SR3 which is connected to repeaters RP1 and RPz through the armature and marking contact M of relay BK3 and the equipment of telegraph station TS. The current through this upper winding of relay SR3 will be a'large current of about 60 ma. and in a marking direction, and the marking effect of the latter current will overcome the spacing effect produced by the resultant current from the batteries B1 and B8 traversing the lower winding of relay SR3. Consequently, the armature of relay SR3 will be held on its marking contact M.

While no signals are being transmitted over the system and the keys of the Various stations are held closed as already stated, the lower winding of relay BK: of repeater R 33 will receive a current from battery B9 which is in a marking direction. This current flows from battery B9, through resistor Z6, the lower windin of relay BKs, resistor Z7 and ground. The upper winding of relay BKs will be devoid of current because it is open-circuited at the spacing contact S of the relay RR3. The dominating current through the lower winding of relay B-K3 will, therefore, hold the armature of this relay on its marking contact M.

Station C may transmit signals over line L3 to repeater RPa which will repeat the signals to repeaters RH and RPz and the latter repeaters in turn will repeat the signals simultaneously to the sounders at stations A and B, respectively. When key K2 at station C is opened for the purpose of transmitting a spacing signal, there will be an absence of current in the upper winding of relay RR3 so that the current in the lower winding of relay RR3, which is in a spacing direction, will move the armature of relay RR3 to its spacing contact S. As the armature of relay RR3 leaves its marking contact M and is still in the air, the current from battery B7 previously flowing through the lower winding of relay SR3 will be removed from this lower winding and hence the only current through the latter winding will be that supplied from battery Ba through re- SiStOI's Z4 and Z5. This current, as already noted, may be a 30 ma. current, and it produces a marking effect on the armature of the relay. This increases the holding action on the armature of relay SR3 to retain this armature on its marking contact M. When the armature of relay RR3 reaches its spacing contact S, additional current will be supplied to the lower winding of relay SR3 to hold the armature of relay SR3 on its marking contact M. This additional current will flow from battery B8, through resistor Z4, the upper winding of relay 3K3, the armature and spacing contact S of relay RR3, the lower Winding of relay SR3 and ground. This additional current, which may be of 60 ma., will be in a marking direction as already pointed out, so that a large resultant marking current will traverse the lower winding of relay SR3. The armature of the relay SR3 will, therefore, be held on its marking contact M even when the flow of current through its upper winding will be interrupted as will be explained hereinafter. The object in holding the armature of relay SR3 on its marking contact when the key K3 at station C is opened, is to prevent a spacing signal from being returned to station C and thereby distort and interfere with the signals to be transmitted.

Upon the closure of contact S of relay RR3, current will flow from battery Ba through resistor Z4 and the upper winding of relay BK3 and this current will be in a direction which tends to move the armature of relay BK3 to its spacing contact S. This current, as'already stated, may be of 60 ma. and it will overcome the biasing effect produced by the current through the lower winding Of relay BK3 which is in a marking direction. Consequently, the armature of relay BK; will move to its spacing contact S. As already stated. the opening of the marking contact M of relay BKw will allow the current through the upper winding of relay SR3 to be reduced to a nullity without causing the armature of relay SR3 to leave its marking contactM.

When the armature of relay BK3 leaves its marking contact M, the current from batteries B5 and Be traversing the circuit of the upper windings of relays SR1 and BK1 of repeater RPi and the lower windings of relays BKz and SR2 of repeater RPz and the sounder SD10 of station TS, will be interrupted. This interruption of current will cause the armatures of these relays just referred to, to move to their spacing contacts S. As the armature of relay SR1 reaches its spacing contact S, the flow of current through the upper winding of relay RR1 over line L1 to the winding of the sounder SDI will be reduced to a nullity to convey a spacing signal to station A. The armature of relay RRi will remain on its marking contact Mbecause the current through the lower winding of this relay will be reversed to a marking direction. Similarly, as the armature of relay SR2 reaches its spacing contact S, the current flowing through the upper winding of relay RRz over line L2 to the sounder SDz will be reduced to a nullity to convey a spacing signal to station E. The armature of relay RRz will also remain on its marking contact M. Thus stations'A and B will receive a spacing signal simultaneously from station C in response to the opening of key K3 at station C.

yteries B and Bo.

and RP3.

5 When the key K3 at station "c is th'e'nclosed to transmit a marking signal tostationsA and B, the armature of relay RR3 will then be controlled by the current in the upper winding of relay RR3 which is in a direction to move the armature of the relay to its marking contact M. When the armature of relay RR3 leaves its spacing contact S and is in the air, the current in the lower winding of relay SR3 will be obtained from batteryBs through resistors Z4 and Z5, and this current will be in a marking direction. -This current will alone be sufficient tohold the armature of relay SRs on its marking contact M. The'current in the upper winding of relay, BK; will be interruptedby the opening of the contact-S of relay RR3, whereupon the current through "the lower winding of relay BK3, which is ina 'marking direction, will cause the armature of relay BK3 to move to its marking contact M. Upon the closure of themarking contact M of relay BK3, ,marking' current from batteries B5 and Be will again traverse the circuit of the upper windings of relays SR1 and BK1, the upper winding of relay SR3, the winding of sounder SD10, andthe lower windings of relays BK2 and SR2. Therefore the armatures of relays SR1, BKI, BK2 and SR2 will be caused to close their markin contacts M. The relays SR1 and SR2 will repeat the marking signals simultaneously over lines L1 and L2, respectively, to the sounders SD1 and SD2 at.

stations A and B. Thecurrent through the upper winding of relay SR3, however, will be a large current of about60' main a marking direction and it will aid the current from battery 'Bs which is traversing the lower winding of relay SR3 through resistors Z4 and Z5. When the armature of relay RR3 reaches its marking'contact M, the current from battery B7 will'again be supplied to the lower windingof relay SR3, the latter current being in a spacing direction. Al though the resultant current in the lower winding of relay SR3 is in a spacing direction, the current in the upper winding of relay SR3 Will be of greater magnitude and in a marking direction" and, hence, the armature of relay SR3 will be held on its marking contact M.

The coil CH is inserted in'series with the battery B7 for the purpose of delayingthe spacing current from battery Br so that this current traversing the lower winding of relay SR3 will become effective only after the upper winding of relay SR3 has received its marking current from battant, for without it the battery'Br may exert'it's spacing effect upon the lower winding of relay 1 SR3 to move its armature prematurely to its spacing contact. S and thereby distort the Si nals intended to be transmitted to stations A and B.

Thus signals may be transmitted from stationv C to the repeater RP3 at station D which then'repeats the same signals faithfully through repeaters RPl and RP2 over lines L1 and L2 to stations A and B, respectively. The'sounder SD 0 of station TS will alsoregister the same signals. Station A may also transmit signals to the other stations. When key K1 is opened to trans,-

This delay feature is imporever, the armatures-of relays SR1 and BK1 will,

mit a spacing signal-to the other stations, the V armature of the receiving relay RRi at repeater RP1 is moved to its spacing contact S." When the armature of relay RRi closes its spacing contact S, battery B11 will be connected to battery-B3 to repeat the spacing signal to repeaters RP2 The circuit connecting batteries Be and B11. may be traced from battery B11} the be held against theirmarking contacts M due to the reversal of current through their lower windings to a markingdirection. On the other hand, relays BK2 and SR2 will close their spacingcon tacts' S upon: the decayof current through their lower windings. The sounder SD10 will repeat the received spacing signal to the telegraph station TS. I

The absence of current in the upper winding of relay SR3 will then allow the lower winding of the relay SR3 to take control of the armatureof that relay. Under the latter conditions the spacing current from battery B7 through the lower winding'ofrelay SR3 will exceed the markin ourrentfrom batteryBa through that winding and, hence, the armature of relay SR3 will 'be moved to its spacin'g'contact'S'. The-relay SR3 will then repeat the spacing signal. over linells' to the sounder SD3 of: station C. The armatureof relay RR3, however, will remain on its markingcontact M While signal are'being'received from station A. The absence of currentin the upper winding of relay BK3 will allowthe lower winding of relay BK3 to retain control of the armature of the relay and, herice,-the-armature of the relay BK3 will remain against its marking contactiM. As the armature of relay SR2 closes its spacing'contactS, as already noted, a spacing signal'wihbe transmitted over lineLz' to sounder SDz. 'The closure of contact S by the armature of relay SR2 will not change'the position of the armature of the relay RR2, the armature 'remaining' against it's contact M. 1 1 'When the key K1 at station 'A is'closed-to transmita marking signal, thearrnature of relay RRi willclose itsmarking 1 contact M, thereby connecting battery B3 to battery B3 over the-oil"- cuit already described heretofore and hencethis descriptionne'ed not be repeated. The large current now traversing th'e lower winding of relay SR2 will cause the-armature of the relaySR2'to close its marking contact M to convey a marking signal over line L2 to the sounder S132 at station B. Again the armature of relay RR2 will become closed against its marking contact M and remain unaffected by signals from station A. The greater current now traversing the upperwinding of relay SR3 will be inia marking direction'an d it will b sufficient toovercome the biasing current through the-lowerwinding-of relay SR3 which is poled in a spacing direction Consequently, the armature of relay SR3 will close its contactM to convey a. marking signal over line L3 tostation' F 0. Againthislwillnot affect the position of the armature, of re1ay-RR3 which will remain against its corltact fM unaffected by signals from station A. Similarly, the armature of relay BK3 will remain against ,its contact M under control ofmarking current'through its lower winding. i Thus station Ai'may eman and spacing signals 'whiclrwillbe repeated {by relay RRl' of repeater fRPi' to-relay SR2-of repeater R1 2 to convey the armature and marking contact -M' of 1 relay 3K1, @7 5 isalne s i gnalsto station B.- In response'to these signals the now" of current through the upper winding of relay SR: will be changed-from a large magnitude in a marking direction for a marking signal to a practical nullity for :a spacing signal so that relay SR3 may convey the same signals to station C without operating relays RR: and BKIl. Moreover, all of these signals will be reproduced by sounder SD at .station TS.

When the operator at station A wishes to break transmission from any of the other stations he will open his key K1. In that event the armature of relay RRi will close its spacing contact S provided relay SR1 has its armature on its contact M. Then batteries B11 and Be will be connected to each other over the circuit including the upper windings of relays SR1 and BKr, the upper winding .of relay SR3, the equipment at station TS, and the lower windings of relays BKz and SR2. The armature of relay BKI will hold its marking contact M closed due to the reversal of current in its lower winding. Also the armature of relay BKa will close its spacing contact S, and relay SR2 will also close its spacing contact "S. The armature of relay RRi will therefore be connected either to battery Be or to battery B14, both of which are poled positively so that the receiving party will receive only positive voltage from repeater RPz. This will effectively break transmission. When the operator at station B wishes to break transmission from any other station, he will likewise open his key K2. In that case the armature of relay RR2 will be connected to batteries B11 and 136, both of which are also poled in a positive direction, thereby likewise breaking transmission. Similarly the relay SR: will cause its armature to close its spacing contact S in response 2 to the opening of the keys at stations A or B to interrupt transmission from' station C. When the operator at station C wishes to break transmission, his opening of key K3 will cause the armature of relay RR; to open it marking contact M, whereupon the armature of relay B-Ka will close its contact S to break the circuit between the upper windings of relays SR1 and BK']. and the lower windings of relays BKz and SR2. This circuit will remain open as long as the key IQ at station C is open. Hence the operators at stations A and B will be apprised of the breaking signal.

It will be observed that the three outlying stations A, B and C are joined together at the repeater point D. The repeater point D has three repeaters RP1, RPz and RP3 which are associated with the respective stations A, B and C. The line terminals of the three repeaters are connected to their associated stations A, B and C by lines Ll, L2 and L3, respectively. The loops of repeaters RP1 and RPz are connected in series with the upper winding of relay SR3 and, the armature and contact M of relay BKa which may be treated as the loop of repeater RPs. The relay SR3 repeats signals from repeater RPiand RPz associated with stations A and B to station C while relay BKa repeats signals from station C to repeaters RH and RPz and thence to stations A and B, respectively. Only three repeaters are required at the repeater point D for the repeater system interconnecting the three stations A, B and C.

Although the stations A, B and C and the loop .station TS are shown to include equipment for Morse signaling, it will be apparent that the equivalent at these stations may be of the teletypewriter type. Teletypewriter equipment at these stations will, of course, make a permanent record of all signals transmitted between the various stations.

Although a station such as station C has been joined to stations A and B by the addition of a repeater such as RPa, other stations may be added to the system by simply opening the circuit between contacts X1 and X2 and inserting a repeater such as RP3 therebetween. A number of repeaters such as RPs may be added in series between points X1 and X2 so that each such repeater will repeat signals in both directions between the stations associated with these additional repeaters and all or the other stations of the system.

A single telegraph station such as TS has been shown inserted between repeaters RP2 and RP3 for illustrative purposes. If desired an additional number of such telegraph loops may be included in series with each other in the circuit to repeat the same signals to each of such additional stations.

The magnitude of the currents referred to hereina'bove have been cited merely to aid in understanding the principles of the invention. Currents of other magnitudes may be used in the practice of the invention, as will be apparent to those skilled in the art.

While the invention has been disclosed in certain particular embodiments merely for illustrative purposes, it will be understood that this invention may be applied to other and widely varied organizations without departing from the spiritof the invention as defined in the following claims.

What is claimed is:

1. In a telegraph repeating system for repeating signals from any one of three lines to the other lines simultaneously, the combination of two repeaters each having a line terminal and a loop terminal, a third repeater having a line terminal, a first relay and a second relay constituting the loop of said third repeater, the line terminal of each repeater being connected to one of said lines, the loop terminals of said two repeaters being connected in series with each other in a series circuit which includes the winding of the first relay of said third repeater and the armature and contact of the second relay of said third repeater, and means whereby said third repeater will send oppositely poled currents over the line associated with said third repeater to repeat signals thereto from either of the other repeaters.

2. In a telegraph system, the combination of three lines, means for repeating signals from any one of said lines simultaneously to the other lines, said means comprising two repeaters each having a line terminal and a loop terminal, a third repeater having a line terminal and a loop, the loop of said third repeater including a first relay and a second relay, the line terminal of each repeater being connected to one of said lines, the loop terminals of said two repeaters being connected in a series circuit which includes the winding of said first relay and the armature and contact of said second relay of said loop, and means whereby said third repeater will sendoppositely poled currents over the line associated with said third repeater to repeat signals thereto from either of the other repeaters.

3. In a telegraph system, the combination of first, second and third telegraph sets, first, second and third repeaters associated respectively with said sets, each repeater including a line terminal and a loop, each of the line terminals of said the loo-p of said third repeater having a first relay for repeating signals from either of the other repeaters to the telegraph set associated with said third repeater and a second relay for repeating signals from the telegraph set associated with said third repeater to the repeaters associated with the other telegraph sets, the loops of said first and second repeaters being connected in series with each other in a series circuit which includes the winding of said first relay and the armature and contact of said second relay of the loop of said third repeater, and means whereby said third repeater will send oppositely poled currents over the line associated with said third repeater to repeat signals thereto from either of the other repeaters.

4. A repeater station comprising three telegraph repeaters for three telegraph sets located at different remote points, each repeater having a line terminal and a loop, the line terminal of each repeater being connected to one of said telegraph sets, the loops of all of said repeatersloeing connected in a common series circuit, one of said repeaters including first and second relays, the winding of the first relay and the armature and contact of the second relay being connected in a series circuit which includes the loop of the latter repeater, and means whereby said third repeater will send oppositely poled currents over the line associated with said third repeater to repeat signals thereto from either of the other repeaters.

5. A repeater station comprising three telegraph repeaters for three telegraph sets located at different remote points, each repeater having a line terminal and a loop, the line terminal of each repeater being connected to one of said telegraph sets, a telegraph loop circuit having a key and a sounder, the loops of all of said repeaters being connected in a series circuit which includes said telegraph loop circuit, one oflsaid repeaters having first and second relays arranged so that the winding of said first relay and the armature and contact of said second relay are connected in series with each other to constitute the loop of said repeater, and means whereby said third repeater will send oppositely poled currents over th line associated with said third repeater to repeat signals thereto from either of the other repeaters.

FRANK HOMER FAY.

ELMER. WILLIAM REEVE. 

